There are many patented devices that apply cyclic pressure to a mammal's limb, arm or foot. In conventional compression devices, the pulsating pads or plunges for improving circulation may be mechanically, hydraulically, or electrically actuated. Elastic and non-elastic stockings, hydraulic and pneumatic bladders or inflatable sleeves may be used to apply controlled levels of compression to an animal's limbs or other body parts. Most suffer varying degrees of shortcomings, including ineffectiveness, difficulties in application and removal, lack of controlled adjustability, loss of compression, excessive sweating, foul odor and discomfort.
These earlier contributions in the art are described in U.S. Pat. No. 5,117,812 to McWhorter; U.S. Pat. No. 5,254,122 to Shaw; U.S. Pat. No. 5,263,473 to McWhorter; U.S. Pat. No. 5,897,518 to Shaw; U.S. Pat. No. 5,989,204 to Lina; U.S. Pat. No. 6,355,008 to Nakao; and U.S. Pat. No. 6,447,467 to Barak. U.S. Pat. No. 5,120,300 and U.S. Pat. No. 5,254,122 relate to therapeutic devices capable of applying therapeutic compression to the body, particularly the limbs, arms and/or feet, in which the user applies non-elastic therapeutic compression band by band, and the user can tighten the compression bands to control the non-elastic pressure. The cyclical and sequential compression of limbs improves blood fluid returns for reducing edema and improving healing.
U.S. Pat. No. 5,897,518 describes a foot and ankle therapeutic compression device in which a pair of foot and ankle compression bands are tightened and anchored in tightened condition by Velcro hook and loop surfaces.
U.S. Pat. No. 5,375,430 describes a gravity powered shoe air conditioner including a compression-expander type cooling or heating system incorporated into a heel of the shoe, and is powered by reciprocal gravity pressure upon the shoe which occurs naturally during walking.
U.S. Pat. No. 5,711,760 describes a self-inflating venous boot comprising a first air chamber having a flexible wall portion adapted to be situated adjacent to the outer surface of the leg, a second air chamber underneath the person's heel, this second chamber forces air out of it when the person's heel bears downward, a conduit means for permitting air flow between the first and second air chambers, whereby air flows between the first and second air chambers. Air flows from the second chamber into the first chamber and pressure cyclically increases in the first chamber urging the wall portion against the leg when the person's heel presses downward on the second chamber. Similarly, air flows from the first to second chamber and pressure on the leg is reduced when the person's heel stops pressing on the second chamber. Some of the disadvantage of this system are: 1) it is not adapted to regulate low-pressure changes 2) it is not automatic 3) it is not tunable and 4) it is not sequential.
In a co-pending U.S. application Ser. No. 09/602,224, now issued as U.S. Pat. No. 6,589,194, is described a self-powered compression device that permits a wearer of a plurality of inflatable sleeves around the limb to apply a controlled level of circular compression to the limb. The self-powered compression device improves the circulation and healing in a variety of vascular circulation problems. However, the device described in the above patent is not adapted to control and regulate low-pressure changes, and therefore optimal performance is not achieved.
The present invention is directed at overcoming one or more of the problems described above.